<!DOCTYPE html>
<html>
<head>
	<meta charset="utf-8">
	<meta name="viewport" content="width=device-width, initial-scale=1">
	<title></title>
	<style type="text/css">
		div:hover{
			background: red;
		}
		div[attr]{
			background: blue;
		}
		
	</style>
</head>
<body>

<div>11111</div>
<div>22222</div>
<div attr='123'>33333</div>
<div>44444</div>
<div>55555</div>


</body>
</html>